Loss of reduces adipogenesis and improves insulin sensitivity in mouse and human adipocytes.

There are multiple independent genetic signals at the () locus associated with type 2 diabetes risk, fasting glucose, ectopic fat, height, and bone mineral density. We have previously shown that loss of in pancreatic beta cells reduces insulin content and impairs islet cell development and function. However, RREB1 is a widely expressed transcription factor and the metabolic impact of RREB1 loss remains unknown. Here, we show that male and female global heterozygous knockout ( ) mice have reduced body length, weight, and fat mass on high-fat diet. mice have sex- and diet-specific decreases in adipose tissue and adipocyte size; male mice on high-fat diet had larger gonadal adipocytes, while males on standard chow and females on high-fat diet had smaller, more insulin sensitive subcutaneous adipocytes. Mouse and human precursor cells lacking RREB1 have decreased adipogenic gene expression and activated transcription of genes associated with osteoblast differentiation, which was associated with mice having increased bone mineral density . Finally, human carriers of T2D protective alleles have smaller adipocytes, consistent with RREB1 loss-of-function reducing diabetes risk.